Wireless charging, also known as Wireless Power Transfer (WPT), is a technology that generally enables a power source to transmit electromagnetic energy across a gap to an electrical load without interconnecting electrical connections. Two types of WPT are radio frequency (RF) based wireless charging and non-radiative or coupling-based wireless charging. RF wireless charging adopts electro-magnetic waves, typically RF waves or microwaves, as a medium to deliver energy in the form of radiation. Non-radiative or coupling based wireless charging is generally based on the coupling of an oscillating magnetic-field established between two coils spaced a relatively small distance apart.
Wireless power transmission systems often include two major components being a power transmitter unit (PTU) and a power receiver unit (PRU). The PTU includes components that supply power to a transmitter resonator coil, which establishes an oscillating magnetic field. The PRU includes a receiving resonator coil that can be magnetically coupled to the transmitter resonator coil. The PRU converts the received alternating magnetic field into electrical energy that can be used to energize or charge a load, such as a battery in a mobile electronic device, a medical device, an electric vehicle or any other apparatus that includes an energy storage device or operates based on wirelessly received energy. In various types of WPT systems there may be a wireless communication path between the PTU and the PRU in order to share static and dynamic charging parameters before and during the time the PTU transfers energy to the PRU.
When a PTU is preparing to or transmitting energy to the PRU, the PTU may want to monitor various aspects of its transmitter resonator coil prior to and during the alternating magnetic coupling with the receiving resonator coil of the PRU. In particular, it may be useful for the PTU to determine prior to transmission whether there is a foreign object proximate to the transmitter resonating coil or between the transmitter and receiver resonating coils. It may also be useful for the PTU to be able to recognize the relative positions of the PTU's transmitting and PRU's receiving coils in order to determine whether an adjustment for a minor misalignment was made, or to not transfer energy wirelessly due to a major misalignment. Additionally, the PTU may want to monitor for a change in the foreign object detection status, relative position status or power transfer efficiency during the transfer of power between the transmitting and receiving coils.
What is needed is a PTU or PRU system that has a device incorporated therein that can be configured to transmit a defined magnetic signal on one or more coils in an array of coils while simultaneously analyzing received magnetic energy on other coils in the array of coils in order to help determine whether a conductive foreign object has become present on the PTU's main transmission coil or aid in the determination of the position of a PRU's receiving coil relative to the PTU's main transmission coil.